abstract:
Jets originating from bottom (b) quarks, play an important role in the
study of Standard Model processes together with the search for new
physics. In the CMS experiment a considerable effort is dedicated to
the development and the performance study of so-called b-tagging
algorithms. On the other hand, the top quark which is produced in pair
with a high rate at the LHC, decays near 99% of the time to a b-quark.
Hence it provides a rich source of b-quark jets, suitable for b-jet
identification studies. In this thesis, a fully data-driven method to
measure the b-tagging efficiency, using top quark events in its
semi-electron final state, is discussed. The result of the application
of the method on the first LHC collisions in 2010 is reported.
The method can be extended to a simultaneous top quark cross section
and b-tagging efficiency measurement, therefore resulting in smaller
uncertainties.